Tilting mechanism for a chair seat or the like

ABSTRACT

A tilting mechanism for a chair seat or the like of the kind where said tilting mechanism comprises a rigid metal plate being connected to a chair support via a retaining means and where said chair seat is pivotally connected to said tilting mechanism by the aid of said retaining means, first and second flexibly resilient and coaxially arranged members e.g., rubber pads or springs, being provided for cooperation with the metal plate and the attaching frame or the like of the chair seat and both said members being provided in front of and spaced from said retaining means so that said first member is compressed when the seat is tilted backwards and that said second flexibly resilient member is compressed when the seat is tilted forwards. Said members are precompressable by the aid of an adjusting member for the adjustment of the tilting rigidity. Said tilting mechanism is provided with locking means to enable locking the seat in a forward tilted, a neutral, or a backward tilted position.

The present invention relates to a tilting mechanism for a chair seat orthe like of the kind where said tilting mechanism comprises a rigidmetal plate being connected to a chair support via a retaining means,said chair seat being pivotally connected with said tilting mechanism bythe aid of said retaining means, first and second flexibly resilientmembers, e.g. a rubber pad or a spring, being provided for cooperationwith said metal plate and the attaching frame of said chair seat or thelike, in such a manner that said first member is compressed when theseat is tilted backwards and that said second member is compressed whenthe seat is tilted forwards.

For a long time it was deemed desirable to provide a chair that may betilted backwards as well as forwards and is in a simple manner lockablein its backwards tilted, forwards tilted, or its intermediate position.A small or large extent of forward tilting of the chair may beespecially suitable for typing or for working at a worktable or thelike, a maximum open angle being then achieved between the upper part ofthe body and the thighs.

The object of the present invention is to provide a technically simplesolution of this problem. According to the invention said tiltingmechanism is characterized in that both said flexibly resilient membersare arranged in front of and spaced from said retaining means, saidfirst member that is compressed when the seat is tilted backwards beingprovided on the lower surface of said metal plate, and the second memberthat is compressed when the seat is tilted forwards being provided onthe top surface of said metal plate, said members being arrangedcoaxially and secured by a screw that extends through said members andsaid metal plate, the upper end of said screw being connected to theattaching frame of the chair seat and its lower end being connected toan adjusting member, whereby the preliminary compression of said membersand, thus, the tilting rigidity are adjustable; and that said tiltingmechanism comprises locking means to lock the seat in a forward tilted,a neutral, or a backward tilted position, said locking means comprisinga stem pivotally connected to said attaching frame of the seat andextending downward through a split in the metal plate and having atleast two locking pins projecting across at different levels, so thatall locking pins will lie in one common level aligned with said splitwhen the stem is turned into a first position in which the seatattaching frame may be tilted freely in relation to said metal plate andthat at least one of said locking pins is brought into contact with aarea on the upper or lower metal plate surface adjacent said split whenthe stem is turned into a second position, or that locking pins arecontacting the upper or lower surface resp. of said metal plate.

The invention will now be disclosed in more detail with reference to theaccompanying drawings, wherein

FIG. 1 shows the tilting mechanism according to the invention inperspective, and

FIG. 2 shows an enlarged section of the tilting mechanism according tothe invention.

In FIG. 1 a rigid metal plate 1 is shown and a retaining means 2 that iswelded to plate 1, as clearly appearing from FIG. 2 as well. Saidretaining means 2 is intended to engage a stem of a support structure,e.g. of an office chair. An attaching frame 5 is provided for the chairseat per se, and said attaching frame is transparent in FIG. 1 tosimplify the drawing, although, it will be obvious that in a practicalembodiment it will consist, e.g. of a rigid suitably bent metal plate.The chair seat is pivotally connected to the tilting mechanism per se bysaid retaining means 2, a shaft 14 protruding on each side of retainingmeans 2 and being supported in suitable bearings 14' in the attachingframe 5, as clearly appearing from FIG. 1. In order to ensure that thechair seat is tiltable in a controlled manner both forwards andbackwards flexibly resilient member 3, 4 are provided in front of andspaced from said retaining means 2. In FIGS. 1 and 2 the arrows A and Bresp. indicate the direction toward the front edge and the rear edgeresp. of the seat. In a similar manner arrows a and b indicate tiltingforwards and backwards respectively. Said members 3, 4 may e.g. eachconsist of a rubber pad or a spring, the first member 3 that iscompressed when the seat is tilted backwards being provided on the lowersurface of metal plate 1, and the second member 4 being compressed whenthe seat is tilted forwards is provided on the top surface of the metalplate. As shown in FIG. 2, said members 3, 4 are coaxial and are securedby screw 6 extending through said members and the metal plate.Corresponding holes are provided in said members and in the metal plate,preferably with a small clearance. The upper screw end is connected andlocked to the chair seat frame 5 by the aid of a locking pin 7, and thelower screw end is connected to adjusting means 8-11; 13. By the aid ofsaid adjusting means the preliminary compression of said members 3, 4and, thus, the tilting rigidity of the seat will be adjustable. Saidadjusting means inter alia comprise a head disk 8 for pressuredistribution, a locking cap 9 preventing the adjusting wheel from beingunscrewed. Adjusting wheel 13 is provided with a nut 21 welded into saidwheel. To ensure simple operation of the adjusting wheel 13, a ballbearing 10 is provided and a steel disk 11 on top of said ball bearing.The disks 8 and 11 and the ball bearing 10 reduce frictional forces whenthe wheel is turned. There is also provided a head disk 12 for pressuredistribution.

The advantage of being able to adjust, i.e. tighten the wheel 13 andthus increase the tension of members 3, 4 is that it is possible in thismanner to compensate for the weight of the user and adapt to the user'srequirement of freedom of movement in the chair. The fundamentalprinciple is that the tilting mechanism is neutrally balanced as astarting point enabling the seat to be tilted forwards (a) or backwards(b).

Pin 7 being arranged in a little recess in the seat attaching frame 5will prevent the screw 6 to turn in relation to said attaching frame.Furthermore, to ensure to the best possible degree that screw 6 cannotturn in relation to the attaching frame 5 and in relation to metal plate1, the hole in said metal plate intended for screw 6 may e.g. have anoval shape, the uppermost part of screw 6 in FIG. 2 having no thread andhaving an oval cross section.

Retaining means 2 and plate 1 are to be considered stationary relativethe tilting of the seat. Members 3 and 4, thus, be decompressed andcompressed respectively when the seat is tilted forwards whereas theopposite takes place when the seat is tilted backwards. To ensure thatthe seat is locked in a most simple manner e.g. in its forward tilted orbackward tilted position or in its central position (neutral position) alocking means is provided the structure and function of which will bedisclosed below.

The locking means comprises a stem 17, e.g. a hexagon bolt, pivotallyprovided in the attaching frame 5. As will appear from FIG. 1, the stem17 can be provided with two through holes across for locking pins 15, 16and uppermost a threaded portion may be provided to be secured to theseat attaching frame 5 by the aid of a nut 19. To ensure a certainfriction between the frame 5 and the stem 17 a spring plate 18 may beprovided. A hand lever 20 is provided for turning stem 17 about itslongitudinal axis, lever 20 being connected to stem 17. Furthermore, aslot 21 is provided in the steel plate 1, and said stem is freelymovable in said slot, although with certain limitations. In FIG. 1 steelplate 1 is shown in a locked position being retained by locking pins 15,16 on the upper and lower side respectively of plate 1. When lever 20 ismoved in direction B pins 15, 16 will be able to pass freely throughsaid slot 21 in the plate 1, and frame 5 will, thus, be able to turnabout turning point 14' in relation to the stationary plate 1. Due tothe fact that frame 5 is movable in relation to plate 1 said stem 17 andthe locking pins 15,16 can also move in split 21 downwards or upwardsdependent on whether the seat is tilting backwards or forwards. When itis desired to lock the seat in the chosen position lever 20 is moved inthe direction A. In FIG. 1 the locking pins 15, 16 are shown withlocking pin 15 provided on the top surface of plate 1 and locking pin 16on the lower surface of plate 1. When the seat is locked in its forwardtilted position both locking pins 15 and 16 will be found on top of theplate, locking pin 16 being in contact with plate 1. In a similar mannerboth locking pins 15, 16 will be found on the lower side of plate 1 whenthe seat is locked in its backward tilted position, locking pin 15 thenbeing in contact with the lower surface of plate 1.

By the solution shown in FIG. 1 there are, thus, in addition to theshown central position provided two lockable positions of the seat, i.e.the chair may be locked in a forward tilted position (writing position)and a backward tilted position. With a tilting mechanism of this kindthe user will have a positive feeling that the chair is properly lockedin these positions, a counter pressure being achieved from said members3 and 4 respectively as disclosed above. The number of lockablepositions of the seat is, however, determined by the number of lockingpins plus 1. By the aid of three or four locking pins totally four orfive lockable positions are, thus, provided. The embodiment shown inFIG. 1 is, thus, not to be regarded as limiting the present invention.The possible angle of the seat will be a function of the distancebetween turning point 14' and locking member 17 as well as the diameterof pins 15, 16.

It will be obvious that a number of modifications of the tiltingmechanism are possible within the scope of the invention. In the shownembodiment the inventor preferred to let the members 3, 4 be rubberpads. There is however, nothing preventing an exchange of the rubberpads with springs.

I claim:
 1. A tilting mechanism for a chair seat, said tilting mechanismhaving a rigid metal plate including lower and top surfaces, a chairsupport, retaining means for coupling said chair support to said metalplate, an attachment frame pivotally connected to said tilting mechanismat said retaining means, first and second flexibly resilient memberscooperating with said metal plate and said attachment frame such thatsaid first flexibly resilient member is compressed when said seat istilted backwards and said second flexibly resilient member is compressedwhen said seat is tilted forwards, wherein:said first and secondflexibly resilient members are arranged in front of and spaced from saidretaining means, said first member being provided on said lower surfaceof said metal plate, and said second member being provided on said topsurface of said metal plate, said first and second flexibly resilientmembers being arranged coaxially, said tilting mechanism furthercomprising a screw extending through said first and second flexiblyresilient members and said metal plate, said screw having an upper endand a lower end, said upper end of said screw being connected to saidattachment frame of said chair seat; adjustment means for adjusting apreliminary compression of said first and second flexibly resilientmembers and for adjusting tilting rigidity, said lower screw end beingconnected to said adjustment member; locking means for locking said seatin forward tilted, neutral, or backward tilted positions, said lockingmeans comprising a stem pivotally connected to said attachment frame,said metal plate having a slot therein, said stem extending downwardthrough said slot in said metal plate, at least two locking pinsprojecting across said stem at different levels, so that all lockingpins will lie in a plane parallel with and extending through said slotwhen said stem is turned to a first position enabling said seatattachment frame to tilt freely in relation to said metal plate and sothat when said stem is turned to a second position either (a) at leastone of said locking pins is brought into contact with a portion on saidupper or lower surfaces of said metal plate adjacent said slot or (b)adjacent locking pins are brought into contact with said upper and lowersurfaces respectively of said metal plate.
 2. The tilting mechanismaccording to claim 1, wherein said first and second flexibly resilientmembers comprise rubber pads.
 3. The tilting mechanism according toclaim 1, wherein said first and second flexibly resilient memberscomprise springs.
 4. The tilting mechanism according to claim 1, whereinsaid locking means further comprises a hand lever coupled to said stemfor turning said stem about said pivot in said attachment frame.